What is a Chemical Reaction? A chemical reaction- is a change in which one or more substances are converted into new substances. An example of this would be a rusty nail. A chemical reaction between the iron in the steel and the oxygen in the atmosphere causes rust. Other examples: lighting a match, start a car, eat dinner or even walking the dog.
Identify the reactants and the products in the following chemical equations. Chemical EquationReactantsProducts 2 Na + S Na 2 S C + O 2 CO 2 CaO O 2 + 2 Ca
Types of Reactions Synthesis/Combination Decomposition Single Displacement Double Displacement Combustion
Synthesis/Combination Occurs when two or more substances combine to form one substance A + B AB Most synthesis reactions involve two elements combining to form a compound
Why is it important to balance reactions? Conservation of Mass Total mass of products equals total mass of reactant Mass is conserved, not created or destroyed Law of Conservation of Mass Video
Balancing Equations Balancing an equation means: changing coefficients so a chemical equation has the same number of atoms on both sides. 4Al + 3O 2 2Al 2 O 3 Coefficients are the numbers that show: how many atoms or molecules of each substance are used or produced. 4Al + 3O 2 2Al 2 O 3
Balancing Equations Subscripts are numbers that show there is more than one atom of a certain type in a molecule of a substance Balance this equation: Fe + 0 2 FeO Fe O
Steps for balancing an Equation 1. Write a chemical equation using formulas and symbols. Fe (s) + O 2 FeO (s) 2. Count the atoms in the reactants and products. reactants products Fe O 3. Choose coefficients to balance the equation. 2Fe(s) + 0 2 2 FeO(s) 4. Check the number of atoms on each side of the equation.